1. Field of the Invention
This invention relates to a method of removing catalyst-poisoning impurities, or contaminants; such as, arsenic or selenium; from hydrocarbonaceous fluids, such as synthetic crude oil and synthetic oil fractions.
2. Description of the Prior Art
There has been a resurgence of interest in sources of energy that were formerly not competitive. These sources of energy include shale oil, such as derived from oil shale; the fluids, such as methanol or coal gas, that are synthesized from coal; the bitumen from the tar sands and the like. Frequently, these fluids are lumped together under generic terms like "hydrocarbonaceous fluids," "synthetic crude oil," or "synthetic oil fractions." Some of these hydrocarbonaceous fluids contain contaminants that would poison expensive catalysts, such as platinum catalysts and the like, that are used in hydrogenation and other processes to which these hydrocarbonaceous fluids must be subjected before they can be satisfactorily used as sources of energy. Even if the hydrocarbonaceous fluids are employed directly as fuels, the removal of the contaminants may be desirable for environmental protection. Consequently, the contaminants must be removed, or have their concentration lowered to an acceptable level.
The prior art has included methods of removing arsenic from hydrocarbon charge stocks, such as described in U.S. Pat. No. 2,778,779. Such methods have included the using of iron, nickel and cobalt oxides to remove arsenic from streams of naturally occurring crude; for example, naphtha or straight run gasoline. In that process, the oxides were employed at a low temperature, such as from room temperature to about 200.degree.F, without regard to the atmosphere under which the reaction takes place and with substantial amounts of water, the oxide acting as an oxidizing agent and oxidizing the arsenic to a water soluble arsenic oxide. In this way, the arsenic oxide is dissolved in the water and removed from the naturally occurring crude oil or oil fraction.
Also, as disclosed in U.S. Pat. No. 2,781,297, arsenic has been removed from similarly naturally occurring crude oils by contacting them with a metallic salt of a strong acid at low temperature, such as room temperature, without regard to the atmosphere under which the contacting takes place. In this particular process, it was taught that oxides do not work for removing arsenic.
One of the most pertinent patents of which we are aware is U.S. Pat. No. 3,496,099, which describes the catalytic hydrogenation of hydrocarbons to effect the precipitation of an insoluble iron salt of the iron porphyrin within a hydrogenating catalyst that increases in concentration longitudinally and concurrently with the flow of the feed; the feed being naturally occurring hydrocarbons.